Conventional plasters have been used for a long time for pattern, model and mold making. Until recently, there was only one material, commonly known as "plaster of Paris". However, "plaster of Paris" does not meet the requirement for dimensionally accurate, automated CNC-machined master patterns and prototypes. More recently, various new materials have been developed in attempts to meet the particular requirements for a viable machinable substrate established by these computer aided carving machines. These include a number of plastic, polyurethane foam board, epoxy wood, machinable wax, monolithic graphite, and ceramic materials. Many of these products, however, are not user or environmentally friendly, and are very costly. Plastics, foams, ceramics, and graphite based products cannot be easily repaired or remodeled, and have a tendency to generate dust when machined. Also, many of these materials need to be disposed of properly as they may create landfill problems.
Therefore, a need still exists for a better material for use in conjunction with computer aided milling machines for precise master model or pattern manufacture. A suitable material must be dimensionally stable from room temperature through 250.degree. F., readily carvable, and able to hold a sharp edge and smooth contour. It should also be environmentally and user friendly, and generate little or no dust when machined.